1. Field of the Invention
This invention relates to pick assemblies for conveying agricultural seed product from a supply thereof to a delivery location and, more particularly, to a pick assembly using a pick to penetrate and frictionally hold the seed product during conveyance thereof.
2. Background Art
Pick assemblies are used on planters to continuously convey agricultural seed product from a supply thereof to a delivery location, as within a furrow, as a towing vehicle for the planter is advanced over a field. Multiple pick assemblies are incorporated into the planter to allow simultaneous planting in spaced rows. In one exemplary form, each pick assembly has a pick wheel that turns around an axis. A plurality of pick arm assemblies are provided around the circumference of the wheel, with each made up of paired pick and stripper arms. The pick arm has a cantilever-mounted pick that is configured to penetrate seed product within a supply so as to cause the same to be frictionally held with the seed product in a holding position. As the wheel turns through a first angular path portion, the seed product in the holding position is conveyed from the supply towards the delivery location. As the wheel moves in another angular path portion, the pick arm cooperates with an actuating assembly that progressively moves the pick arm relative to the stripper arm, as an incident of which the stripper arm draws the seed product off the pick, whereby the seed product is allowed to move under its own weight to the delivery location.
Each of the picks has a nominally cylindrical shape with a lengthwise axis extending between a mounting end and a free end. The free end has a sharpened point to facilitate its entry into seed product. The body of the pick tapers progressively from the free end over at least a portion of the length of the body so as to produce a wedging action as the pick penetrates a seed product.
To allow the picks to fully penetrate the seed product, the picks have a relatively slender configuration. After extended periods of use, the picks abrade and may become dull, bent, otherwise reconfigured, or broken. Thus, it is anticipated that periodic replacement of the picks will be necessary. When it becomes necessary to replace some or all of the picks, the planting vehicle is in a down state. Accordingly, it is desirable to facilitate mounting and replacement of the picks in a manner whereby this task can be carried out quickly and easily.
Designers of picks are motivated by objectives that often compete with each other. First and foremost, the picks must be effective from an operational standpoint. Second, they must be durable with an adequate life in a relatively harsh environment. Third, they must be relatively inexpensive since it is expected that they will be replaced periodically.
From an operational standpoint, it is critical that the holding characteristics of the picks be such that they can be readily advanced into the seed product and at the same time frictionally held therewithin so that they do not prematurely release the seed product as the pick wheel is advanced. Consistent seed spacing accounts for uniform crop size, which maximizes price that can be demanded for a crop. Skipping of a seed placement and double seed placement impair this uniformity. Thus, the picks must be designed so that each engages and delivers one and only one seed product for each wheel revolution. A seed product that is not appropriately held may release from a pick prematurely, resulting each time in the skipping of a seed placement.
Heretofore, to generate an appropriate holding force between the picks and seed product, aside from producing a tapered construction that produces a wedging action, the exposed surfaces of the picks have been effectively roughened to increase frictional holding forces between the exposed pick surface and the inside of the penetrated seed product. These surfaces have been roughened in the past by forming continuous shallow rings, threads, etc.
Picks have been made from metal in the past. The roughening or texturing of the exposed surfaces thereof may be imparted through a machining operation that is carried out as, or after, the picks are blanked. Metal products, while durable, represent potentially a significant financial investment in terms of the material, the blank formation, and any subsequent processing thereof. The industry has generally been willing to make the additional financial investment in metal picks to reduce the incidence of breakage. Broken picks account for skipped delivery of seed product, which compromises crop yield and quality.
Ideally, the picks are designed so that they are convenient to install and replace with a minimal time investment, effectively hold seed product during operation of the equipment, are durable to have an adequate life, and at the same time are relatively inexpensive so that they can be regularly replaced without a burdensome financial investment. Designers in this industry continue to strive towards a design that meets the above design criteria.